Mayza, 27, will miss the entire 2020 season.
With one on and none out in the top of the 10th inning on Friday, Mayza delivered a pitch to outfielder Cameron Maybin. The pitch was wild and Mayza immediately grabbed his pitching arm. Team trainer Nikki Huffman went to the mound and accompanied Mayza off the field after a brief conversation.
Ryan Tepera replaced Mayza, who had a 4.91 ERA with 55 strikeouts in 51.1 innings entering play Friday.